Table of Contents
Advertisement
Inspection and Testing
Inspection and Testing
Before the equipment is energized, it must be thoroughly
inspected and tested. Correct any deviations before energization.
Inspection
Check the following points:
1. High voltage connections properly insulated.
2. Electrical disconnecting contacts, machined parts, shutter,
etc., checked for lubrication and operation.
3. Blocking, supports and other temporary ties removed from
breakers, instruments, relays, etc.
4. Proper fuses correctly placed.
5. Temporary wiring jumpers (used on the secondaries of
current transformers wired to external devices, as shown
on wiring diagrams) removed.
6. Ground connections properly made.
7. Incoming primary and secondary connections properly
made and checked for shorts or undesired grounds.
8. All equipment which has been removed during assembly
has been replaced.
9. Relays coordinated with other relays and protection
devices on the system. Refer to relay instructions before
making any adjustments. Consult the local utility before
making any connections to the power supply.
10. Storage battery fully charged and provided with recharging
facilities.
11. Interlocks performing properly.
12. Circuit breakers checked and prepared per instruction
books.
13. All filters in vent areas are clean and free of shipping or
construction material.
Testing
1. An insulation resistance test is made on the high voltage
circuit to be sure that all connections made in the field are
properly insulated. An insulation resistance test is also
advisable on the control circuit.
2. A dielectric test, if possible, should be made on the high
voltage circuit for one minute at one of the following voltages
corresponding to the rated voltage of the equipment.
(Note: Voltage transformers, control power transformers,
surge arresters, and surge capacitors must be discon-
nected during this test).
Rated
Power
Maximum
Frequency
Voltage
Withstand
kV (rms)
kV (rms)
4.76
19
8.25
36
15
36
Note: The DC test voltage is given as a reference only for
those using DC tests to verify the integrity of connected
cable installations without disconnecting the cables from the
switchgear. It represents values believed to be appropriate
and approximately equivalent to the corresponding power
frequency withstand test values specified for each voltage
rating of switchgear. The presence of this column in no
way implies any requirement for a DC withstand test on
AC equipment or that a DC withstand test represents an
acceptable alternative to AC withstand tests. When making
44
Courtesy of NationalSwitchgear.com
Field Test Voltage
kV (rms)
kV (dc)
14.25
20.2
27
38.2
27
38.2
DC tests, the voltage should be raised to the test value in
discrete steps and held for a period of one minute.
In accordance with ANSI C37.20.2 Clause 5.5, Field
Dielectric Tests are also recommended when new units
are added to an existing installation, or after major field
modifications. The equipment should be put in good con-
dition prior to the field test. It is not expected that
equipment shall be subjected to these tests after it has
been stored for long periods of time or has accumulated a
large amount of dust, moisture, or other contaminants
without being first restored to good condition.
A dielectric test on secondary and control circuits should
be made for one minute at 1125 volts AC or 1590 volts
DC. The above voltages are in accordance with NEMA
Standards. (Note: Certain control devices, such as motors
and motor circuits, should be tested at 675 volts AC.
Electronic devices should be tested at the voltages spec-
ified in the instruction manual for the electronic device).
Excessive test voltages.
May result in damage to equipment.
Do not perform dielectric tests at test voltages
exceeding the ratings of the tested equipment.
3. With breaker in the TEST position make the following
tests on each unit:
A. Trip and close the circuit breaker with the control
switch.
B. Trip the breaker by passing sufficient current (or voltage,
if applicable) through the coils of protective relays.
C. Trip and close the breaker from any remote control
locations.
D. Operate auxiliary devices.
E. Test the phase sequence of polyphase high voltage
circuits, particularly those used for motor starting.
Placing Equipment into Service
To place equipment in service for the first time proceed as
follows:
1. Check that all circuit breakers are open and all control
circuits energized.
2. Connect primary incoming power source to equipment.
3. Check all instruments, relays, meters, etc., during this
time.
4. Connect as small a load as possible and observe instruments.
Note: Allow several minutes before connecting additional
load.
5. Gradually connect more load to the equipment while
observing instruments until the full load is connected.
6. Check for signs of overheating of primary and secondary
circuits and satisfactory operation of all instruments during
the first week of operation.
CAUTION
Advertisement
Table of Contents
